Total and complete mystery - suddenly NO water out of hot supply to tub

I re-did my bathroom about 5 years back, and the kitchen immediately below the bathroom 2 years ago.

Everything has been fine for years. Good pressure both hot and cold.

My tub is a clawfoot with a newer Porcher tub filler. 2 Dahl mini-ball finishing valves are stubbed out from the wall for the supply to the tub.

The other night, wife goes to run a bath and no hot water. I go in, turn on the hot, and it works. Chalk it up to the Fonz effect I seem to have on anything she says doesn't work (ranging from the TV to the computer to the water).

Next night, she goes to do the same, and nothing. Not a drop.

So - clearly it must be the cartridge. I decide to step past that and go straight to the mini-ball valve. Disconnect the braided supply line from the mini-ball valve (after turning it off) and slowly open it up. Nothing!

Now of course I think it's the valve. I happen to have a thin piece of copper wire - fish it through the open valve and it passes easily. Today, I turned off the hot water and removed the compression fit valve. Just a copper stub sticking out of the wall. Turn the water back on, and NOTHING. Not a drip, not a hint of moisture coming out.

There is hot water everywhere else, including the shower which branches off this supply in the floor. Hot water in the laundry, next to the bath. Everywhere but the bathtub.

The copper plumbing in this house is perhaps 15-20 years old at most. Anyone have any insight into how a 1/2" soldered copper line gets clogged, and not just partially, but completely, what must be within a couple feet of the stub out of the wall? Any further back and it would effect the shower as well.

I'm at a loss, and have little interest in opening up walls or tearing up 80 sq ft of heated marble floor that is only 5 years old.

There's a 90 elbow about 8 inches in from the wall, and no obstructions to that point. I don't have anything flexible yet stiff enough to fish further into the copper line.

While yes it is on an exterior wall, its in an insulated riser along with the cold supply and drain stack. I'm in Toronto, and its a 90 year old solid brick home - i.e. the walls are about 10" thick solid brick. But regardless, it does get cold, but not that cold, and in the 13 years I've owned the house I've never had a frozen pipe.

It's bizarre. Worst case scenario I have to rip up the marble flooring, but spending $3-$4K to replace it all for a silly problem like this would drive me around the bend.

If I ever build a custom home, every inch of plumbing and electrical will be either exposed or in accessible compartments

I have a digital thermometer with a probe that fits into a 3/16 hole. If is is below freezing outside for a couple of weeks, it will be below freezing on the inside of a brick wall which is insulated from the interior.

Here in the north, it's pretty common to stub up supply piping through the floor an inch or two to the INSIDE of the finished wall if you must plumb on an outside wall.

Because heating water drives out some of the dissolved gasses, once it cools back off in the pipe, it tends to freeze sooner than the cold line...it's been really cold this week in the north...once it does thaw, you may have a split pipe or fitting.

Here's the thing - this one line supplies both the tub and the shower with hot. The shower runs fine. It branches off perhaps 2 - 3 feet from the tub shutoff, in the floor.

The supply lines for both hot and cold come up from the kitchen below, in a corner bulkhead with the stack. The copper is about 10 inches in from the brick and the entire space is insulated.

The lines for the tub come up through the floor, about 6 inches out from the exterior wall. We built a 2x4 framed wall against the brick which is insulated. The pipes come up from the floor in front of that framed wall into a small knee wall as you can see in the pics. In the floor, under the tub, the lines branch off towards the shower.

Here are some additional pics. I agree with everything said - it's been a cold winter (not the coldest we've had since the bathroom was done) and a frozen pipe is the most likely cause of this, but again, it was utterly sudden and it's in the last 2-3 feet of copper leading to the tub.

My wife runs a hot bath (more or less all hot) every single night and has done so since I did the bath 5 years ago. This was a sudden stoppage 2 nights ago. I'm completely stumped. Unfortunately opening up the floor is the only viable way to get at the pipes. The kitchen cabinets are immediately below and go to the ceiling. I'd much sooner rip up marble flooring than deal with the kitchen.

Thankfully I used the area under the tub as my overflow area for my heating cables. I might get away with pulling up the last row of tiles closest to the wall and not destroy the rest of the floor. Luckily I took pics of my install.

Not holding my breath that I can surgically cut through the tile, thinset, Ditra, thinset, Russian birch ply and 3/4 ply under that, but I can hope

And I'm in Toronto, where the coldest it has gotten is about -15 celsius outside at night. This is not abnormal for us in a given winter.

I grew up in Winnipeg where it was -30 all the time. So no doubt pipes are freezing all over the place there, but not here.

Clearly I'll be keeping an eye on it in case something goes sour inside the wall/floor and I all of a sudden have water running and pouring out my kitchen recessed fixtures.

Going to reach out and try to get a reputable professional in here to have a look with perhaps the right tools to run into the pipe to see if we can reach an obstruction or measure temp. Aside from that I have no idea where to start aside from a hammer and chisel on my tile.

Here's the thing - this one line supplies both the tub and the shower with hot. The shower runs fine. It branches off perhaps 2 - 3 feet from the tub shutoff, in the floor.

Click to expand...

Maybe you could get lucky and thaw it by running the hot water in the shower. The heat should migrate down the pipe past the Tee.

What can happen is that there is some air infiltration through the insulation that carries away the heat resulting in the frozen pipe. The area between the ceiling below and the floor is difficult to insulate and seal against air infiltration.

My guess is the lines are frozen in the wall and not under the floor. If you used the same insulating board over the studs that you used on the side wall you have insulated the water lines from the heat in the room. Insulation doesn't create heat.

The little knee wall / whatever you want to call it behind the tub is not full of insulation, only the wall behind it. The hot water has been in use multiple times daily up in the bathroom with the shower and sink in use, and there isn't even the hint of a trickle coming out of this one pipe.

I know the only logical explanation is a frozen pipe, as even solder excess from a lousy joint done years ago breaking off inside the pipe wouldn't likely cause a perfect seal.

If I were a betting man, I'd put money on it being in the floor joist cavity caused by air infiltration due to stack effect.

Two things need to be done. 1: The source of cold needs to be stopped. 2: A source of heat is needed. Crack open a window downstairs to reduce the infiltration. This should lower the neutral pressure plane. Raise the temp in the kitchen by turning up the heat. Run the hot water in the shower on trickle long enough to get the heat on the pipe to spread past the Tee.

If i didn't have the patience to "wait & see", I would drill a hole in the wall where the riser is and start blowing some room-temp air in there. Since you know exactly how the bump-out is constructed, maybe you can pull the top off for access without destroying anything visible.

Alright - so after a bit of a warmer day (around freezing) we have a dribble. Then I used a turkey baster to squirt some hot water from the kettle into the copper pipe from the top (after turning the hot water off at the tank) and then turned the pressure back on. Steady dribble.

Reconnected the valve and braided lines to the tub, put the drain back in and opened up the hot. Few minutes of dribble and the flow increased back to normal. Cold water came out with the dribble.

So no doubt it was frozen. Coincides with the coldest day we had in the last 2 years, which happens to be since we did the kitchen below. Ironically having replaced the windows, insulated the exterior walls etc. we end up with this problem. My plumber never suggested (and I of course didn't think) that we move the supply lines out of that riser in the outside corner of the house. Could have done it easily and for nothing at the time of course. It was May when we did the work. Perhaps plumbing should only be done when it's the coldest time of the year so you think about these things

Good news is nothing seems to have burst or broken. When everything is shut tight, there doesn't appear to be any water movement. So I'm cautiously optimistic that I don't have a leak in my wall.

Plan is to open up the kitchen ceiling drywall and re-configure the supplies so I'm not using those in the outside corner riser. Then, into the basement where I'll open up more drywall and (crosses fingers) isolate the lines that cross the basement ceiling from the inside wall (this is a semi-detached house and the hot water tank etc. is on the shared wall side) that run up into the 2nd floor. With luck I'll be able to cut and cap the lines after any branches that I need to maintain for the kitchen sink etc.

Nothing like doing things 3x Just last fall I ripped out the basement powder room I did 13 years ago (my first introduction to the older Terry Love forums - http://terrylove.com/wwwboard/messages/8180.html) after having the clay drain pipes inspected. Turned out we had a little root infiltration where the new ABS stack interface with the clay, right under the basement bathroom. So out it went, ripped up the concrete and had a gazillion dollars worth of new plastic drain installed. That did allow the reconfiguration of the basement bath to include a shower which was nice, but it meant ripping up the finished floor in part of the basement as well so I replaced 500 sq ft of 13 year old glued Pergo with engineered hardwood to match the main floor I had just done.

Anyhow - taps are on trickle - both hot and cold (cold never froze which is bizarre as they run right beside each other in exactly the same place). Going up to 12 above celsius this week so we're out of the cold spell.